What Causes Down Syndrome

Topics: Down syndrome, Gene, Chromosome Pages: 1 (258 words) Published: March 21, 2013
What causes Down syndrome?Charlie Zammit
To this day, there aren’t any known environmental or behavioral factors that cause Down syndrome. The human contains 23 pairs of chromosomes, so 46 individual ones. From each pair, one comes from your father, the other, from your mother. Down syndrome involves an abnormal cell division in chromosome 21. There are three types of abnormal cell division that can occur to cause Down syndrome; all of the three cell division abnormalities create a problem being extra genetic material from chromosome 21. The three genetic variations that cause Down syndrome are translocation Down syndrome, mosaic Down syndrome and trisomy 21. Down syndrome is 9 out of 10 times caused by trisomy 21. Translocation Down syndrome is a very uncommon form of Down syndrome. It occurs when a section of chromosome 21 becomes translocated to another chromosome at or before conception. If a person is diagnosed with translocation Down syndrome, they still have all the normal chromosome 21 cells as well as additional material from chromosome 21 attached to the attached chromosome. Mosaic Down syndrome is the rarest of the three forms of Down syndrome. It is when some cells with an extra copy of chromosome 21 are found in the body. It is caused by abnormal cell division after fertilization. The last of the three forms of Down syndrome is trisomy 21. Trisomy 21 has three chromosomes 21 instead of the normal two in every cell. This is caused by abnormal cell division during the development of either of the sex cells.
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